In recent years, the number of lifestyle-related disease patients has increased in accordance with the westernization of a dietary life, and medical and social problems become serious. Currently, it is said that the number of diabetic patients is 8 million in Japan, and the number thereof reaches 20 million if a potential group thereof is included. Three major complications of diabetes are “retinopathy, nephropathy, and neuropathy”, and further diabetes becomes a main cause of arteriosclerosis, and even heart disease and brain disease are concerned.
Diabetes occurs from deficiency of insulin which controls a blood glucose level or insulin malfunction, resulting from pancreas malfunction caused by an eating habit disorder, a lifestyle habit disorder, an influence of a secretion from fat cells due to obesity or oxidative stress. If diabetes occurs, the number of times or an amount of urination is increased, and a symptom such as thirst appears, but there is no subjective symptom of the disease in a case of only the symptom, and the disease is mostly discovered by a test in a hospital or the like. This is the reason why there are many “silent” diabetic patients.
There are many cases where the symptoms have already progressed after the abnormal symptoms due to the complications that appear in the hospital or the like, and it is difficult to completely cure the symptoms. In particular, the complication is unlikely to be cured, and prevention is regarded as important in the same manner as other lifestyle-related diseases. Early detection, and curative effect judgment are indispensable in order to perform prevention, and a large number of diabetes tests aiming for that are present.
If oxidative stress is added under an environment where an abnormal amount of carbohydrates or lipids are present in the blood, a reaction of proteins with carbohydrates or lipids occurs, and AGEs (advanced glycation end products) are generated. The AGEs are final products that are formed by a non-enzymatic glycosylation reaction (Maillard reaction) of proteins, and are materials exhibiting yellowish brown color, and emitting fluorescence, and have properties of forming a crosslink by combining with proteins which are present in the vicinity thereof.
The AGES are said to develop arteriosclerosis, by depositing or infiltrating into a wall of a blood vessel, or by acting on macrophage which is in charge of a portion of the immune system and releasing cytokine being one type of protein thereby causing inflammation.
Since the AGEs are also increased in accordance with the increase of blood glucose in the case of diabetes, it is possible to realize early detection of diabetes or grasp the progress state of diabetes, by monitoring the AGEs. In this manner, as a method of screening for diabetes mellitus by monitoring the AGEs, for example, a method disclosed in PTL 1 is reported.
In this method, the AGEs are monitored by irradiating the skin of a forearm with excitation light, and measuring a fluorescence spectrum from the AGEs which are combined with skin collagen, and comparing the measured fluorescence spectrum with a predetermined model. Hereby, data of the AGEs is obtained without invasiveness.
In PTL 2, a detecting device that specifies an optimum position of a relative position between a subject and a light-receiving portion receiving the fluorescence which is emitted by the subject, based on an intensity of the received light which is received by the light-receiving portion, is disclosed.
In PTL 3, a device that monitors the AGEs by being put on an earlobe is disclosed. It is possible to miniaturize the device, by making a relatively small region such as the earlobe in the human body as a measurement target region.
Moreover, technologies disclosed in PTL 4 to PTL 6 are used as examples of measuring devices which make the relatively small region in the human body as a measurement target region although not being monitoring devices for the AGEs. These devices are devices that make a fingertip as a measurement target region, and measure oxygen saturation in blood or a pulse wave.